Many electric plugs have been designed with locking means adapted to releasably lock the plug in a wall outlet to prevent accidental uncoupling of the plug. However almost without exception the releasable locking means of the prior art take the form of spring-loaded pushbuttons designed to disengage the plug from a wall outlet simply by manual manipulation, typical of which are the releasable locking means shown in U.S. Pat. Nos. 3,676,831 Bergwall 7/11/72; 3,267,408 Baker et al. 8/16/66; 2,985,119 Montgomery, Jr. 7/14/59 and 2,885,650 Miller et al 5/5/59. Other forms of releasable locking means have taken the form of cam arrangements wherein partial rotation of one element of the plug retracts the plug locking means, as illustrated by U.S. Pat. Nos. 3,159,445 Wolk 12/1/64 and 2,750,570 Bates 6/12/56.
However while these and similar plug locking means serve to prevent inadvertant or accidental disengagement of a plug from its wall outlet the plug can be readily unlocked by anyone in a relatively quick and simple manner.
However with the increase in crime rate and in particular the number of home burglaries which take place annually wherein homes are ransacked of portable electrical appliances such as TV sets, Hi-Fi equipment, radios, lamps and the like such losses could be prevented or at least significantly reduced provided the plugs of such electrical appliances are locked to the wall outlets in a manner such that the plugs could be released only by authorized persons.